It is known to provide a sprinkler having a valve member retained in a closed position by a latch means. It is known to provide a temperature responsive means for releasing such a latch means. It is desirable to use a bulb of glass or other frangible material and containing a temperature responsive fluid as the temperature responsive means. In order for such a bulb to be sensitive, it should be small and have very thin walls. Since the bulb is used as a latch retainer, the fluid system pressure is so high so as to preclude use of bulbs which are small and thin-walled.
The present invention is directed to a solution of the problem of how to reduce compressive forces on the bulb whereby the bulb may be smaller and thinner than prior art bulbs.